Currently, disposable razors provide a substantial portion of the market for wet shaving.
With the exception of the blade or blades (and possibly a spacer) the disposable razors are made out of thermoplastic material. The cap and blade support or seat components, depending upon the ultimate design, are molded separately and then assembled. For example the "MicroTrac" disposable razor manufactured by Gillette holds a single unit blade seat, back and cap with the cap including outwardly extending fingers. The blade subassembly consisting of two blades and a spacer is inserted between the molded cap and seat with the finger-like projections extending from the top of the cap serving as leaf springs to retain the blade subassembly. This combination is then mated to a handle by press fitting into the tab-finger combination. It is apparent that this process involves not only separate steps, but separate work stations requiring individual sub assembly and ultimate assembly.
Other assembly processes for disposable razors utilize staking from projections depending either from the cap or the seat, which mate with reciprocal openings in the other part and position the blades and/or spacer. The handle is usually made separately from the seat portion. Again, separate assembly steps at separate locations are required to produce the disposable razor.
Ultimately, a disposable razor which could be assembled with a single work station having all the plastic parts produced in a single cavity would be desirable because the steps of subassembly, final assembly and the conveying of the various components from location to location around the manufacturing area could be eliminated. Prior art patents have disclosed various attempts to accomplish this.
U.S. patent application Ser. No. 615,603 filed in the name of Ernest F. Kiraly et al on May 31, 1984 describes a razor with a blade having a slot therein. According to the application, the blade is permanently secured in the head portion of the razor and the handle and guard portion are molded integrally with the head.
British Patent 1,565,296 cited during the prosecution of the above-referred to application discloses making a unitary handle guard member and blade support and then attaching a z-shaped blade by upset rivets, or the like to the support.
U.S. Pat. No. 4,489,627 issued Dec. 27, 1984 to Lembke describes a razor manufacturing process in which a double edged strip of blade metal is parted along a center line and cropped to form two strips, each containing a series of spaced apart blades connected by webs to an elongate backing strip. Each strip, which now consists of a plurality of blades and a backing strip, is fed into a molding machine in which, either the shaving unit or blade-containing-component of a razor, is molded directly around each individual blade. The web is then parted to release the molded razor, etc. from the backing strip. It is unclear, according to Lembke, how the remaining razor components are manufactured. It is apparent, however, that the molding machine completely surrounds the blade segment during molding. Lembke, therefore, requires the handling of an elongated metal strip, its control and insertion in either a multi-cavity mold or a very large single cavity mold and either a series of razors or heads joined together in a single unit which must be subsequently disassembled. Conveying of a metal web of the type described in extremely difficult when it is necessary to protect a delicate cutting edge and even more so when two cutting edges must be protected.
U.S. Pat. No. 3,209,409 to K. L. Grathwohl describes injection molded razors made in packs wherein pins having a relatively small cross sectional diameter clamp the blade on its top and bottom face. Unfortunately there is insufficient support from these pins to prevent blade distortion as the hot fluid plastic rushes around the blade during the molding process. Also, shaving debris would collect in the resultant cap and seat holes which is, at the very least aesthetically undesirable.
Other patents disclosing molding a plastic razor head around a blade are U.S. Pat. No. 3,070,883 (Grathwohl); U.S. Pat. No. 2,789,346 (Algier et al.); and U.S. Pat. No. 3,703,765 (Perez).